A Papua New Guinea MP claims asylum seekers made threats to rape the mothers and sisters of local Manus Island detention centre guards in the lead-up to Monday's deadly riots.Manus MP Ron Knight alleges G4S guards were subjected to foul language and abuse from asylum seekers."They made sexual (comments), saying they were going to get out and rape their mothers and their sisters," he told AAP."It started with them - they got nasty and they broke down the gate."Mr Knight, who is in Port Moresby for parliamentary sittings and was not on the island at the time, said a PNG defence force officer gave him that account over the phone as the drama was unfolding."He was standing quite close to the fence, by a coconut tree, observing everything," Mr Knight said.PNG police are investigating and Australia's immigration department will appoint an independent person to review the incident.Operation Sovereign Borders commander Lieutenant General Angus Campbell assessed security measures on the island on Thursday and is due to return to Australia in the evening.But it remains unclear what sparked the riot that killed a 24-year-old Iranian man and injured 76 other asylum seekers, with five requiring medical evacuations, including one man who was shot in the buttocks.PNG newspaper The National is reporting that the asylum seekers in detention at Manus Island submitted a list of 14 questions about their welfare and future to Australian authorities before the violence erupted on Sunday and Monday.The questions reportedly asked their status, when they would be released, where they would be resettled, why the media are banned from detention centres and a plea for mental health support.The Australian Greens have called for a royal commission into the incident and Labor is asking for a government explanation."I do think that the Abbott government would be wise to dispense with its addiction to secrecy," Opposition Leader Bill Shorten told reporters in Melbourne.Prime Minister Tony Abbott said his government would not be intimidated into backing away from its strong border protection stance."We will not succumb to pressure, to moral blackmail," Mr Abbott told reporters in Sydney."We will ensure these camps are run fairly, if necessary, firmly."He said Australian authorities acted swiftly to secure the centre after the disturbances.The centre has resumed operations and asylum seekers are being properly fed and cared for, Mr Abbott said.The Law Council of Australia welcomed inquiries into the violence by PNG police and Australia's Department of Immigration and Border Protection.But in a statement, the council said independent oversight of detention facilities was essential to ensure they operated in accordance with the rule of law."Those seeking asylum in Australia, irrespective of where they are being processed and detained, should be treated with dignity and fairness in accordance with Australian and international standards, and that their health and safety is paramount," the statement said.